Norway Proposed Projects that Deal With Its Very Deep Waters Like, An UnderSurface Water Vehicular Tunnel that is Held In Place by Weights, Floating Pontoons, and Tethered to the Sea Floor. Here Though They Propose A Floating Suspension Bridge!!

Norway is getting a floating suspension bridge tethered to the bottom of the sea - and it could change the way we make bridges

Norway could soon be home to a floating, multi-span suspension bridge in unprecedentedly deep waters. Bridge engineer Ian Firth discussed the bridge, which will cross a long and deep Norwegian fjord known as Bjørnafjord, during a talk at this week's TED Conference. Bridge foundations in deep water can be incredibly expensive.

From article, (Bridge engineer Ian Firth discussed the 3-mile-long bridge, which will cross a long and deep Norwegian fjord known as Bjørnafjord, during a talk at this week's TED Conference in Vancouver, Canada.

Bridge foundations in deep water can be incredibly expensive. But the Bjørnafjord bridge gets around that by floating.

"We've had floating bridges before, but nothing like this," Firth, a consultant at Cowi (one of the organizations working on the bridge), said during his talk.

The Bjørnafjord bridge will stand on floating pontoons that will be tethered to the seabed. In order to create stability, the tops of the bridge's towers will be tied together. A similar floating design has been used for oil platforms in the past — but never for multi-span suspension bridges until now.

"Floating bridges tend to be shorter span," Firth told Business Insider. "This [bridge] is seriously large."
The bridge project, which is being spearheaded by the Norwegian Public Roads Administration, could open up all sorts of possibilities for new crossings in waters that were previously thought to be too deep for bridges to be built. (This technology allows bridges to be placed in water that's nearly 5000 feet deep.)
 There is still a long way to go before this kind of bridge technology becomes commonplace, however. The Bjørnafjord bridge's materials are well understood, but there are construction challenges, including the building and maintenance of the top cables. The bridge will actually last longer than the cables — which support the bridge — so replacements will have to be made available.

"Nobody wants to do something that's been unproven and yet everybody wants to be the first," Firth said. "Once we've sold the technical challenges, it will reach that sweet spot where the economics become something that's doable."

No word yet on when the bridge will be completed, but it likely is still several years away.)

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